Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New discovery blurs distinction between human cells and those of bacteria

10.08.2005


UCLA biochemists reveal the first structural details of a family of mysterious objects called microcompartments that seem to be present in a variety of bacteria. The discovery was published Aug. 5 in the journal Science.



"This is the first look at how microcompartments are built, and what the pieces look like," said Todd O. Yeates, UCLA professor of chemistry and biochemistry, and a member of the UCLA-DOE Institute of Genomics and Proteomics. "These microcompartments appear to be highly evolved machines, and we are just now learning how they are put together and how they might work. We can see the particular amino acids and atoms."

A key distinction separating the cells of primitive organisms like bacteria, known as prokaryotes, from the cells of complex organisms like humans is that complex cells -- eukaryotic cells -- have a much higher level of subcellular organization; eukaryotic cells contain membrane-bound organelles, such as mitochondria, the tiny power generators in cells. Cells of prokaryotes have been viewed as very primitive, although some contain unusual enclosures known as microcompartments, which appear to serve as primitive organelles inside bacterial cells, carrying out special reactions in their interior.


"Students who take a biology class learn in the first three days that cells of prokaryotes are uniform and without organization, while cells of eukaryotes have a complex organization," Yeates said. "That contrast is becoming less stark; we are learning there is more of a continuum than a sharp divide. These microcompartments, which resemble viruses because they are built from thousands of protein subunits assembled into a shell-like architecture, are an important component of bacteria. I expect there will be a much greater focus on them now."

Yeates’ Science paper reveals the first structures of the proteins that make up these shells, and the first high-resolution insights into how they function.

"Those microcompartments have remained shrouded in mystery, largely because of an absence of a detailed understanding of their architecture, of what the structures look like," said Yeates, who also is a member of the California NanoSystems Institute and UCLA’s Molecular Biology Institute. "The complete three-dimensional structure is still unknown, but in this paper we have provided the first three-dimensional structure of the building blocks of the carboxysome, a protein shell which is the best-studied microcompartment."

The UCLA biochemists also report 199 related proteins that presumably do similar things in 50 other bacteria, Yeates said.

"Our findings blur the distinction between eukaryotic cells and those of prokaryotes by arguing that bacterial cells are more complex than one would imagine, and that many of them have evolved sophisticated mechanisms," Yeates said.

While microcompartments have been directly observed in only a few organisms, "surely there will be many more," Yeates said. "The capacity to create subcellular compartments is very widespread across diverse microbes. We believe that many prokaryotes have the capacity to create subcellular compartments to organize their metabolic activities."

Yeates’ research team includes research scientist and lead author Cheryl Kerfeld; Michael Sawaya, a research scientist with UCLA and the Howard Hughes Medical Institute; Shiho Tanaka, a former UCLA undergraduate who is starting graduate work at UCLA this fall in biochemistry; and UCLA chemistry and biochemistry graduate student Morgan Beeby.

The structure of the carboxysome shows a repeating pattern of six protein molecules packed closely together.

"We didn’t know six would be the magic number," Yeates said. "What surprises me is how nearly these six protein molecules fill the space between them. If you take six pennies and place them in the shape of a ring, that leaves a large space in the middle. Yet the shape of this protein molecule is such that when six proteins come together, they nearly fill the space; what struck me is how tightly packed they are. That tells us the shell plays an important role in controlling what comes in and goes out. When we saw how the many hexagons come together, we saw that they filled the space tightly as well."

The UCLA biochemists determined the structures from their analysis of small crystals, using X-ray crystallography. How microcompartments fold into their functional shapes remains a mystery.

Yeates’ laboratory will continue to study the structures of microcompartments from other organisms.

If microcompartments can be engineered, biotechnology applications potentially could arise from this research, Yeates said.

Stuart Wolpert | EurekAlert!
Further information:
http://www.college.ucla.edu

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>